Such cam carriages are known from, for example, applicants' unpublished patent application (P 36 30 051.9) and from German Laid-open Application DE-OS No. 32 45 230 (U.S. Pat. No. 4,502,300). In both cases the bottom plate is rigidly connected with the top plate; in the first case the top plate is moved back and forth by a driven link plate via a link roller engaging the cam of a link plate, while in the other case the top plate of the draw-down element is moved in the direction of draw-down by a gear rack against the effect of a draw spring. This rigid connection between the respective operational element and the draw-down element has, besides the advantage of a restraint and of sufficient force application in the course of shifting of the takeoff element into one of the draw-down positions, the disadvantage that shifting during lifting of the cam carriage can lead to malfunctions if, for example, one of the needles is sluggish or if, because of the knots and/or enlargements in the knitted fabric, the correct drawing movement of particular needles is not possible, or if the yarn is overstressed by extreme pulling. This can result in breakage of the needles and/or the yarn or in overloading of the step motor for the draw-down element(s). A further disadvantage results from the fact that during shifting of the draw-down position the transition from a tight to a loose loop is too abrupt, which has an adverse effect on the appearance of the knitted fabric and which possibly can also lead to breaks in the yarn.
On the other hand, a cam carriage is known from German Patent DE-PS No. 33 10 671 (U.S. Pat. No. 4,554,802) and from German Laid-open Application DE-OS No. 30 50 591 (U.S. Pat. No. 4,510,775) in which the draw-down element also consists of rigidly connected top and bottom plates. However, the casting-off element is biased by a tension spring in the draw-down direction which pulls the draw-down element against a respective drive element in the respective draw-down position. However, this had the disadvantage that in the respective draw-down position the force of the tension spring pulling the draw-down element into this position is at its weakest and this results in a draw-down force which does not satisfy the requirements. In other words, the draw-down force in the selected draw-down position can be so slight that individual needles change their selected draw-down position in an upward direction. However, an increase in the draw-down force exerted by the tension spring is not possible because of the corresponding force increase when moving the draw-down element into the alignment position.